The present invention relates to a ball screw Z stage for use in wafer probers.
The use of a ball screw is a common practice for moving a load along a constrained axis. Constraining the other axes is normally accomplished by conventional bearings.
In prior art approaches in wafer prober technology, to obtain adequate cross axis torsional stiffness with a conventional bearing-based stage requires a relatively long (or tall in the case of a Z stage) constraint. One particular approach utilizes long journal bearings to support the Z stage. This construction technique at least doubles the working plane height. The result of the taller Z stage is increased XY positioning errors, such as due to dynamic effects.
It would be desirable to provide an improved Z stage support which overcomes such deficiencies in prior art approaches.